FAQ: Google Chrome ad blocking is here. Everything you need to know

How it works, who will be affected and what it means for advertisers, publishers and users.

Today, February 15, 2018, is the day Google begins blocking “annoying” or intrusive ads by default in its Chrome browser. Publishers that repeatedly serve up obnoxious ads after they’ve been flagged will find all of their ads, even those served by Google, blocked by Chrome.

Here’s our guide to understanding why Google is doing this, how it all works and what impact ad blocking in Chrome may have on publishers, advertisers and users.

What are the blocking criteria?

Google is using the Coalition for Better Ads‘ Better Ads Standards for determining what makes an obnoxious ad experience for users. Examples include video ads that play at full volume, flashing display ads, popups with hard-to-find exit buttons and prestitial ads that block users from seeing content on the page.

The 12 ad formats were deemed particularly annoying based on the Coalition for Better Ads survey data. Source: Coalition for Better Ads

An example of an ad experience that didn’t make the annoying list is anchor ads which remain at the bottom or top of the screen as users scroll. Based on surveys of 25,000 internet users in North America and Europe conducted by the Coalition (though namely by Google), roughly 85 percent of mobile users surveyed said they found anchor ads only a little annoying or not annoying at all.

Ranking of mobile web ad experiences from most to least preferred. Source: Coalition for Better Ads

How does Google evaluate if sites are adhering to the Better Ads Standards?

Google evaluates a sample of pages from a publisher’s site and gives it a Passing, Warning or Failing grade based the percentage of page views in the sample that contain poor experiences that don’t meet the Better Ads Standards. The Coalition guidelines establish failing thresholds as:

7.5 percent of page views in the first two months of the program.

5 percent in the four months following.

2.5 percent thereafter.

Publishers can see whether they have received any “warning” or “failing” assessments in Google’s Ad Experience Report, made available last fall in Google Search Console.

A site will have 30 days after being notified of violations to fix any non-compliant ad experiences. If it fails to do so, Chrome will begin to block ads on that site.

When a site fails, how does Chrome ad filtering work?

In a blog post published Wednesday, engineering manager Chris Bentzel provided more color on how the ad filtering in Chrome works.

When someone navigates to a site in Chrome, the browser’s ad filter checks to see if the page the user is visiting is part of a site that has failed the Better Ads Standards.

If it is on a “failing” grade site, Chrome checks the network requests — for images or JavaScript, for example — against a list of known ad-related URL patterns. It will block any network requests that match against that list and block the ad from displaying on the page.

The known ad-related URL patterns are based on the EasyList filter lists, a public set of rules to filter out URL patterns matching known ad suppliers, including Google AdSense and DoubleClick. It was first developed for the content-filtering (i.e., ad-blocking) Adblock plugin for Mozilla and Firebird browsers. EasyList is now the main list of filters used by all ad blockers.

Once at least one ad-related network request has been blocked, users will see a message that the ads have been blocked and will have the option to “allow ads on this site.” The notification will appear in the address bar on desktop. On Android devices, the notice will appear at the bottom of the screen as shown in the sequence below.

On Android devices, users will see a notice at the bottom of the screen alerting them that ads have been blocked. Tapping for more details allows users to “always allow ads on this site.”

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Why is Google doing this now?

The move by Google is driven largely in response to the rising adoption of ad blockers on desktop and the threat of adoption on mobile. Chrome holds roughly 50 percent of the mobile browser market share worldwide and roughly 45 percent in North America.

Research firm eMarketer estimated that last year, 28 percent of desktop/laptop internet users in the US would be using ad blockers, and 11.8 percent of smartphone users.

“We’ve already seen more and more people express their discontent with annoying ads by installing ad blockers, but blocking all ads can hurt sites or advertisers who aren’t doing anything disruptive. By focusing on filtering out disruptive ad experiences, we can help keep the entire ecosystem of the web healthy, and give people a significantly better user experience than they have today,” wrote Rahul Roy-Chowdhury, a Google vice president of product management, in a blog post this week.

Sridhar Ramaswamy, Google’s head of ads and commerce, called ad blocking in Chrome “the ultimate fall back option” at a conference for publishers last fall. “Our hope is once this is in place, there’s no need for ad blocking on mobile,” he said at the time.

The world’s biggest ad seller is the arbiter of ads on the world’s biggest mobile browser?

Why, yes it is! Google is a member of the Coalition for Better Ads, along with more than 15 other companies and trade groups, including Facebook, Microsoft and the IAB. But just as Google has dominated the open-source AMP Project, it also has been the dominant voice in the Coalition for Better Ads.

As soon as there was a hint of Google’s ad-blocking plans for Chrome, there were critics crying foul. On the one hand, no one can really argue against cleaning up the most annoying of ad experiences. And if any entity is going to have the muscle to do it, it’s going to be the biggest player in the field. On the other hand, Google is playing both sides of the field as ad seller and gatekeeper. Will it favor its own formats and own ads?

The company has been emphatic that its own ads will be treated equally and adds that its ads will be blocked on offending sites along with all the other ads. Google’s Chris Bentzel concludes his post saying the company looks forward “to continued collaboration with the industry toward a future where Chrome’s ad filtering technology will not be needed.”

However, The Wall Street Journal reported [pay-wall] yesterday that some people involved with the Coalition said the process of determining which ad formats to block “wasn’t a true joint effort but a Google-dominated one that, while reducing ads widely considered annoying, also could ultimately help Google’s bottom line.” Google has confirmed the Coalition’s research used to create for Better Ads Standards was in fact conducted by Google. Google, of course, makes the lion’s share of its ad revenue from search ads, not the kinds of display ads on Coalition’s blacklist.

Echoing another concern, Wes MacLaggan, SVP of marketing at Marin Software, said in a phone interview Tuesday, “It also has the possible side effect of driving advertisers to Google’s stack to ensure delivery.”

Others have also pointed out that this move does nothing to address concerns about tracking, the data from which underpins Google’s ad business. The European Commission has also signaled it will be looking closely at how Chrome’s ad filtering plays out.

Will anyone notice?

In an ongoing audit of 100,000 sites in Europe and North America, Google says .9 percent would have their ads blocked. Another .5 percent of those sites are at the “warning” level of having their ads blocked, Axios reported this week.

Chris Bentzel says in his post, “As of February 12, 42 [percent] of sites which were failing the Better Ads Standards have resolved their issues and are now passing.”

As for the impact on ad blocker usage, we’ll have to see. “The actual launch is not going to be game-changing. People aren’t going to uninstall ad blockers but may slow future adoption,” predicts Marin’s MacLaggan.

Chrome ad blocking can also be viewed as part of a continuum of steps Google has been taking to improve mobile experiences — and keep people engaging with ads.

About The Author

Ginny Marvin is Third Door Media's Editor-in-Chief, managing day-to-day editorial operations across all of our publications. Ginny writes about paid online marketing topics including paid search, paid social, display and retargeting for Search Engine Land, Marketing Land and MarTech Today. With more than 15 years of marketing experience, she has held both in-house and agency management positions. She can be found on Twitter as @ginnymarvin.